150 Miscellaneous. 



Although in general form and proportion of its parts, especially of 

 the terminal style of its abdomen, the specimen of this species in the 

 British Museum agrees exactly with St. Leonum, yet the short third 

 joint of the antennse, and the extraordinarily enlarged size of the 

 middle facets of the inner margin of the eyes, might indicate it to be 

 the opposite sex of the preceding. The second segment of the abdo- 

 men is furnished on each side with a small fascicle of elongated black 

 hairs. 



This species is introduced by Mr. F. "Walker into his ' List of the 

 Dipterous Insects in the Collection of the British Museum' (part iii. 

 p. 680), under the name of Stylogaster stylatus ; but it appears to 

 me that it neither accords with Macquart's generic characters oi Sty- 

 logaster, nor with the concise Fabrician specific description of Conops 

 stylata (Syst. Antl. 177), nor yet with "Wiedemann's more detailed 

 observations, especially with reference to the sexual difference in the 

 form of the antennae (Auss. Eur. Zw. Ins. ii. 245). 



MISCELLANEOUS. 



Observations on the Circulation of the Blood in the Arachnids. 

 By M. Emile Blanchard. 



Until very lately the circulatory apparatus of the Arachnida re- 

 mained nearly unknown. It was supposed, indeed, that the pulmo- 

 nary Arachnida would resemble the Crustacea in their mode of cir- 

 culation, whilst the tracheary Arachnida, on the other hand, would 

 resemble insects ; but observations on this subject are still almost en- 

 tirely wanting, and all the peculiarities belonging to the type remained 

 unknown. The question, however, made a great step, as far as regards 

 the ScorpionidcB, in consequence of the researches of Mr. Newport ; 

 and in a memoir published three years since, I described the course 

 of the principal arteries in the Araneidce, in which they had not as yet 

 been traced. Notwithstanding the appearance of these works, many, 

 points remained to be cleared up. A new examination of this circu- 

 latory apparatus has recently led me to ascertain its details in a tole- 

 rably complete manner. I had made my previous researches on spe- 

 cies found in France, which are of very small size ; but, during last 

 autumn, a very lively specimen of a Mygale of the largest dimensions 

 {M. Blondii), which inhabits South America, having been received 

 at the museum, I have derived considerable assistance from it, in 

 the investigation which I have long been pursuing, on the anatomy 

 and physiology of the Arachnida. I injected this Mygale, intro- 

 ducing the injection by the heart, and succeeded by this means in 

 following, and isolating by dissection, all the arteries distributed to 

 every organ, even to "their most delicate ramifications. 



In this short abstract of my labours, I abstain from describing the 

 course of these numerous arteries in detail, as the description will ap- 

 pear shortly in my work entitled ' L' Organisation du Regne Animal.' 

 I content myself here with indicating the general result ; a result 

 which does not apply only to the species which has served me in a 



